1. Field of the Invention
Aspects of the present invention relate to a supported catalyst and a fuel cell using the same, and more particularly, to a high-concentration, high-dispersity carbon-supported catalyst with improved catalytic efficiency manufactured using a polyol process, in which metal catalyst particles, such as platinum, are impregnated on a surface of a carbon-based catalyst support through a polyol process so as to form a mono-layer structure or multi-layer structure, and a fuel cell using the carbon-supported catalyst.
2. Description of the Related Art
Fuel cells are sources of clean energy and have the potential to replace fossil fuels, since they have a high power density and a high energy-conversion efficiency. Fuel cells can be operated at an ambient temperature and can be miniaturized and hermetically sealed. Thus, fuel cells can be used in a wide range of applications such as zero-emission vehicles, household power generating systems, mobile telecommunications equipment, medical equipment, military equipment, space equipment, and portable electronic devices.
Proton exchange membrane fuel cells (PEMFCs) or direct methanol fuel cells (DMFCs) are power-generating systems that produce direct current through an electrochemical reaction of methanol, water, and oxygen. These fuel cells include an anode and a cathode where liquid and gas are supplied and have a structure in which a proton conductive membrane is interposed between the anode and the cathode. A catalyst is contained in the anode and the cathode. The catalyst in the anode decomposes hydrogen or methanol to form protons which pass through the proton conductive membrane and react with oxygen in the presence of the catalyst in the cathode, as part of an overall process that generates electricity.
As described above, the catalyst is contained in the cathode and/or anode of the fuel cell to promote the electrochemical oxidation of fuel and/or the electrochemical reduction of oxygen.
In PEMFCs, a catalyst with platinum particles dispersed in an amorphous carbon support is used as the catalyst for the anode and the cathode. In DMFCs, PtRu is used in the anode, and platinum particles or a catalyst that has platinum particles dispersed in a carbon support is used in the cathode.
Methods of manufacturing a supported catalyst with platinum particles or platinum-ruthenium particles dispersed in a carbon support are disclosed in U.S. Pat. Nos. 6,686,308 and 6,551,960.
According to the methods of manufacturing described in the above-identified patents, if metal catalyst particles such as platinum particles are dispersed in the carbon support, the platinum particles may be covered with carbon particles to such an extent that the weight of the metal catalyst particles increases by 80% or more. An increase in the size of the metal catalyst particles leads to problems in impregnation. Thus, catalytic activities and uses decrease, leading to a decline in the performance of unit cells.